Photographic developer



Patented Nov. 15, 1938 UNITED STATES 2,136,968 PATENT. OFFICE PHOTOGRAPHIO DEVELOPER.

Albert n. Doran, Hollywood, calm, ammo: to Carns Chemical Company, Inc., a corporation of Illinois No Drawing. Application October 26, 19st,

Glaims.

This invention relates to an agent for developing light sensitive photographic images and more particularly to a developing agent designed for quick development of silver images in a colloidal I l5 On the other hand, there are available certain other'developers which will produce fine grain butrequire 'very long periods of development, for example, as much as twenty-four hours or more.

tion of fine grain images without resultant decrease in the speed of development. By "benzene type developer is meant a benzene derivative containing at least two groups selected from the class consisting of hydroxy amino and sulfonic acids and preferably hydroxy or amino.

The addition of minute amounts of a thic- 30 cyanate has proved particularly advantageous in connection with such compounds in accelerating the speed of thedevelopment without producing enlarged grain size. The amount of'thiocyanate must be kept quite low because higher quantities 5 'act as silver solvents and adversely affect the films.

Any soluble stable thiocyanate, such as KSCN must be employed, and the compound may be incorporated in quantities ranging from one per- 40 cent downward, normally to as low as based on the organic developing agents.

The following is an example of a suitable photo graphic developer for use on motion picture films.

5 Moho-chlom-hydroquinone.---grams The following example is a suitable formula 55 for fine grain positive development or the development of flne grain plates from a negative,.

either of sensitized paper, motion picture film, or other light sensitive mediums. Like the preceding formula, it may be modified to suit the re- 60 quirements or the worker. For developing the While these products produce It has now been discovered that the addition of a halogenated hydroquinone to a salt of a primary aryl amine developer results in the produc therefrom, but the appended claims should be Serial No. 107,736

ordinary sensitized paper. the solution may be used as shown, or with equal parts or water. For enlarging papers the solution should be diluted with tour parts of water. For negative and panchromatic film the solution may be diluted with 5 4, or 5 parts of water. v

Mono-chloro-hydroquinone grams.. 1. 5 Methyl-ortho-amino-phenolsmfntp (In 1.5 Potassium thiocyanate ..do 8 Sodium sulflte do 80 Hydroquinrmn (19 3 Sodium carbonate do 0 v Potassium bromide -do 1 Potassium metabisuliite do 1 Water c. 0.... 1

The following are additional examples of materials which in combinationproduce suitable developers: Y l 20 1 A halo-hydroquinone and hydroxymethylparaminophenol sulfate.

.2. A chloro-hydroquinone and mono-methyb' paraminophenol sulfate.

3. A halo-hydroquinone andmethyl-ortho-amino-phenol sulfate;

4. A halo-hydroquinone hydrochloride.

The reason for the eflect of the halogenated or the thiocyanate compound upon the other developer is not understood. It is possible that the presence oi the halogen has some eiiect upon the release or interchange of halogen radicals upon the silver in the film.

The thiocyanate is efiective with benzene type .developers in general.

The foregoing detailed description has been given for clearness of understanding only and no unnecessary limitations should be understood and diphenyl-aminoconstrued as broadly as permissible in viewoi' .the prior art.

I claim:

Q 1. A photographic developer comprising approximately equal proportions of mon'o-chlorohydroquinone, methyl-ortho-amlno-phenol sulfate and .02 rto 1 percent of a thiocyanate based on the total weight of the developers.

2. A photographic developer havingsubstantially the following formula:

Mono-chloro-hydroquinonegrams 1.5 Methyl ortho amino phenol sulfate h g' ams 1.5

Potassium thiocyanatedo .003 Sodium sulflte do Hydroquinone do 5 Borax do 5 Water 0 c- 1000 30 tially the following formula:

Mono-chloro-hydroquinonegrams Methyl ortho amino phenol sulfate 5 gra.ms Potassium thiocya'nate do Sodium sulfite do Hydroquinone do Sodium carbonate do 10 Potassium bromide do Potassium metabisulfite do Water o. c

4. A rapidly acting photographic developer comprising a. salt of a primary aryl amine developer, a halogenated hydroquinone and a thiocyanate, the thiocyanate being present in amount from approximately .02% to 1%, based on the organic developers present.

5. A developer as set forth in claim 4 in which the thiocyanate is potassium thlocyanate. 

